21424727 has 4 divisors (see below), whose sum is σ = 21476280. Its totient is φ = 21373176.

The previous prime is 21424699. The next prime is 21424759. The reversal of 21424727 is 72742412.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21424727 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21424727.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21424787) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 25148 + ... + 25985.

It is an arithmetic number, because the mean of its divisors is an integer number (5369070).

Almost surely, 2^21424727 is an apocalyptic number.

21424727 is a deficient number, since it is larger than the sum of its proper divisors (51553).

21424727 is an equidigital number, since it uses as much as digits as its factorization.

21424727 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 51552.

The product of its digits is 6272, while the sum is 29.

The square root of 21424727 is about 4628.6852344915. The cubic root of 21424727 is about 277.7400006878.

The spelling of 21424727 in words is "twenty-one million, four hundred twenty-four thousand, seven hundred twenty-seven".